Engineered bio-inspired coating for passive flow control

Humberto Bocanegra Evans, Ali M. Hamed, Serdar Gorumlu, Ali Doosttalab, Burak Aksak, Leonardo P. Chamorro, Luciano Castillo

Research output: Contribution to journalArticle

Abstract

Flow separation and vortex shedding are some of the most common phenomena experienced by bluff bodies under relative motion with the surrounding medium. They often result in a recirculation bubble in regions with adverse pressure gradient, which typically reduces efficiency in vehicles and increases loading on structures. Here, the ability of an engineered coating to manipulate the large-scale recirculation region was tested in a separated flow at moderate momentum thickness Reynolds number, Re- = 1, 200. We show that the coating, composed of uniformly distributed cylindrical pillars with diverging tips, successfully reduces the size of, and shifts downstream, the separation bubble. Despite the so-called roughness parameter, k+ ≈1, falling within the hydrodynamic smooth regime, the coating is able to modulate the large-scale recirculating motion. Remarkably, this modulation does not induce noticeable changes in the near-wall turbulence levels. Supported with experimental data and theoretical arguments based on the averaged equations of motion, we suggest that the inherent mechanism responsible for the bubble modulation is essentially unsteady suction and blowing controlled by the increasing cross-section of the tips. The coating can be easily fabricated and installed and works under dry and wet conditions, increasing its potential impact on a diverse range of applications.

Original languageEnglish (US)
Pages (from-to)1210-1214
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number6
DOIs
StatePublished - Feb 6 2018

Fingerprint

coatings
bubbles
modulation
bluff bodies
separated flow
flow separation
vortex shedding
blowing
suction
pressure gradients
falling
Reynolds number
vehicles
equations of motion
roughness
turbulence
hydrodynamics
momentum
shift
cross sections

Keywords

  • Adverse pressure gradient
  • Bio-inspired surface
  • Engineered surface
  • Flow control
  • Flow separation

ASJC Scopus subject areas

  • General

Cite this

Engineered bio-inspired coating for passive flow control. / Evans, Humberto Bocanegra; Hamed, Ali M.; Gorumlu, Serdar; Doosttalab, Ali; Aksak, Burak; Chamorro, Leonardo P.; Castillo, Luciano.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 115, No. 6, 06.02.2018, p. 1210-1214.

Research output: Contribution to journalArticle

Evans, Humberto Bocanegra ; Hamed, Ali M. ; Gorumlu, Serdar ; Doosttalab, Ali ; Aksak, Burak ; Chamorro, Leonardo P. ; Castillo, Luciano. / Engineered bio-inspired coating for passive flow control. In: Proceedings of the National Academy of Sciences of the United States of America. 2018 ; Vol. 115, No. 6. pp. 1210-1214.
@article{cdb9a78f04d1480d89cb53dda9a7f940,
title = "Engineered bio-inspired coating for passive flow control",
abstract = "Flow separation and vortex shedding are some of the most common phenomena experienced by bluff bodies under relative motion with the surrounding medium. They often result in a recirculation bubble in regions with adverse pressure gradient, which typically reduces efficiency in vehicles and increases loading on structures. Here, the ability of an engineered coating to manipulate the large-scale recirculation region was tested in a separated flow at moderate momentum thickness Reynolds number, Re- = 1, 200. We show that the coating, composed of uniformly distributed cylindrical pillars with diverging tips, successfully reduces the size of, and shifts downstream, the separation bubble. Despite the so-called roughness parameter, k+ ≈1, falling within the hydrodynamic smooth regime, the coating is able to modulate the large-scale recirculating motion. Remarkably, this modulation does not induce noticeable changes in the near-wall turbulence levels. Supported with experimental data and theoretical arguments based on the averaged equations of motion, we suggest that the inherent mechanism responsible for the bubble modulation is essentially unsteady suction and blowing controlled by the increasing cross-section of the tips. The coating can be easily fabricated and installed and works under dry and wet conditions, increasing its potential impact on a diverse range of applications.",
keywords = "Adverse pressure gradient, Bio-inspired surface, Engineered surface, Flow control, Flow separation",
author = "Evans, {Humberto Bocanegra} and Hamed, {Ali M.} and Serdar Gorumlu and Ali Doosttalab and Burak Aksak and Chamorro, {Leonardo P.} and Luciano Castillo",
year = "2018",
month = "2",
day = "6",
doi = "10.1073/pnas.1715567115",
language = "English (US)",
volume = "115",
pages = "1210--1214",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "6",

}

TY - JOUR

T1 - Engineered bio-inspired coating for passive flow control

AU - Evans, Humberto Bocanegra

AU - Hamed, Ali M.

AU - Gorumlu, Serdar

AU - Doosttalab, Ali

AU - Aksak, Burak

AU - Chamorro, Leonardo P.

AU - Castillo, Luciano

PY - 2018/2/6

Y1 - 2018/2/6

N2 - Flow separation and vortex shedding are some of the most common phenomena experienced by bluff bodies under relative motion with the surrounding medium. They often result in a recirculation bubble in regions with adverse pressure gradient, which typically reduces efficiency in vehicles and increases loading on structures. Here, the ability of an engineered coating to manipulate the large-scale recirculation region was tested in a separated flow at moderate momentum thickness Reynolds number, Re- = 1, 200. We show that the coating, composed of uniformly distributed cylindrical pillars with diverging tips, successfully reduces the size of, and shifts downstream, the separation bubble. Despite the so-called roughness parameter, k+ ≈1, falling within the hydrodynamic smooth regime, the coating is able to modulate the large-scale recirculating motion. Remarkably, this modulation does not induce noticeable changes in the near-wall turbulence levels. Supported with experimental data and theoretical arguments based on the averaged equations of motion, we suggest that the inherent mechanism responsible for the bubble modulation is essentially unsteady suction and blowing controlled by the increasing cross-section of the tips. The coating can be easily fabricated and installed and works under dry and wet conditions, increasing its potential impact on a diverse range of applications.

AB - Flow separation and vortex shedding are some of the most common phenomena experienced by bluff bodies under relative motion with the surrounding medium. They often result in a recirculation bubble in regions with adverse pressure gradient, which typically reduces efficiency in vehicles and increases loading on structures. Here, the ability of an engineered coating to manipulate the large-scale recirculation region was tested in a separated flow at moderate momentum thickness Reynolds number, Re- = 1, 200. We show that the coating, composed of uniformly distributed cylindrical pillars with diverging tips, successfully reduces the size of, and shifts downstream, the separation bubble. Despite the so-called roughness parameter, k+ ≈1, falling within the hydrodynamic smooth regime, the coating is able to modulate the large-scale recirculating motion. Remarkably, this modulation does not induce noticeable changes in the near-wall turbulence levels. Supported with experimental data and theoretical arguments based on the averaged equations of motion, we suggest that the inherent mechanism responsible for the bubble modulation is essentially unsteady suction and blowing controlled by the increasing cross-section of the tips. The coating can be easily fabricated and installed and works under dry and wet conditions, increasing its potential impact on a diverse range of applications.

KW - Adverse pressure gradient

KW - Bio-inspired surface

KW - Engineered surface

KW - Flow control

KW - Flow separation

UR - http://www.scopus.com/inward/record.url?scp=85041508895&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85041508895&partnerID=8YFLogxK

U2 - 10.1073/pnas.1715567115

DO - 10.1073/pnas.1715567115

M3 - Article

AN - SCOPUS:85041508895

VL - 115

SP - 1210

EP - 1214

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 6

ER -